The present invention relates to a vehicle for transporting goods, such as a trailer, a semi-trailer or a rigid. More particularly, the invention relates to such a vehicle having a deformable roof whose shape can be adapted in order to improve aerodynamics.
For many years, attempts have been made to improve vehicle efficiency. One factor in an efficient design is the aerodynamic characteristics of a vehicle. The air drag of a vehicle and especially of an industrial vehicle such as a truck is one of the factors that has a direct impact on fuel consumption. Therefore, in a general trend towards rare and expensive energy—whether fossil or not—, aerodynamics is one of the key issue in an efficient vehicle.
One problem with the current vehicles is that air flowing upwardly along the windshield then passes longitudinally rearward above the roof of the vehicle and tends to deviate outward from said roof. Such an air path is not favourable because it causes turbulence and, moreover, contributes to the creation of a low pressure area behind the vehicle. This increases the vehicle drag coefficient and, consequently, generates a high fuel consumption. It is estimated that the aerodynamic drag of a long haul truck entails a consumption of around 40%-60% of the engine power on a flat road at cruising speed.
Several devices have been added to vehicles in order to reduce turbulence, in particular to prevent air from deviating away from the vehicle roof. However, these devices don't make it possible to adapt the shape of the vehicle roof to improve aerodynamics depending on the current conditions. Moreover, many of these known devices can require specific, fragile and/or costly equipment.
It therefore appears that, from several standpoints, there is room for improvement in industrial vehicles aerodynamics.
It is desirable to provide an improved vehicle which can overcome the drawbacks encountered in conventional vehicles.
More particularly, it is desirable to provide a vehicle having a cargo body with a lower aerodynamic drag.
The invention relates, according to an aspect thereof, to a vehicle for transporting goods, such as a trailer, a semi-trailer or a rigid, said vehicle comprising a cargo body having a roof made being deformable.
According to an aspect of the invention, the deformable roof can be placed:                in a neutral position, where said deformable roof forms substantially a flat surface parallel to a floor of the cargo body,        or in at least one aerodynamic position, where at least a rear portion of the deformable roof is lowered with respect to the neutral position.        
Thus, in a vehicle according to an aspect of the invention, it is possible to give the roof of the cargo body an aerodynamic shape. With such a shape, where the rear portion of the roof is lowered, the air passing above the roof is made to substantially follow said roof instead of deviating from it, which limits turbulence and aerodynamic drag.
Moreover, depending on the current conditions, the roof of the cargo body can be given a neutral shape, where generally the cargo body has the shape of a parallelepiped.
The roof is made of a deformable material, i.e. a material which has the appropriate mechanical strength to resist the stress it undergoes in use, but which can be elastically extended from the neutral position to the aerodynamic position or vice versa. For example, the roof can be made of a semi-rigid material or can comprise a flexible cover.
In a preferred embodiment, in the aerodynamic position, the deformable roof has a profile which progressively drops rearwards. Then, the roof shape is similar to the top surface of an airfoil profile, which is particularly efficient in terms of aerodynamics.
It can further be envisaged that, in at least one aerodynamic position, a front portion and/or a rear portion of the deformable roof is raised with respect to the neutral position. With a from part of the roof which is not a flat portion but a rising curved portion, while the rear part is lowered, the aerodynamics of the vehicle can be further improved.
Transition of the roof between a neutral and an aerodynamic position can be controlled manually or can be automatically controlled by control means.
In an advantageous implementation of an aspect of the invention, the roof position can be controlled as a function of the vehicle speed. This makes it possible to adapt the aerodynamic shape of the roof to the air flow passing above said roof, and therefore to further improve the overall aerodynamics.
There may also be provided on the vehicle external detection means in order to automatically cause the lowering of the deformable roof in case the aerodynamic position is higher than the neutral position and an external obstacle is detected.
The vehicle may further comprise internal detection means in order to automatically determine, the lowered position of the roof as a function of the load in the cargo body.
For example, the vehicle further comprises a plurality of supporting means which are arranged at intervals between a support surface of the cargo body and the deformable roof of the cargo body and which are capable of supporting said deformable roof, at least some of the supporting means being capable of placing said deformable roof in said neutral and aerodynamic positions.
In practice, each supporting means is capable of supporting an area of said deformable roof. In order to place said area of the deformable roof in the appropriate position, the supporting means can either be active means which are capable to pull or push the deformable roof, or passive means which support said deformable wall or do not when they are retracted, so that the deformable wall collapses.
The supporting means may also be capable of placing the corresponding area of the deformable wall in an appropriate intermediate position between the neutral position and the aerodynamic position.
The supporting means can be provided at least at the rear portion of the cargo body, for example at least at the rear third of the cargo body, so that at least the rear portion of the deformable roof can adopt an aerodynamic profile, which results in a reduced low pressure drag area behind the vehicle.
In an advantageous way, the supporting, means are provided substantially in the whole length of the cargo body, so that substantially the whole deformable roof can adopt an aerodynamic profile, which further improves the aerodynamics. In concrete terms, there are successive supporting means, and not continuously arranged supporting means.
For example, at least some of the supporting means are capable of lowering the rear portion of the deformable roof with respect to the neutral position, and/or at least some of the supporting means are capable of raising at least the front portion of the deformable roof with respect to the neutral position, so as to give the cargo body roof its aerodynamic shape.
The vehicle can further comprise means for actuating the supporting means between a neutral and an aerodynamic position, and said actuating means can be controlled manually or remotely controlled by control means. The supporting means can be actuated independently the one from the others or, alternatively, can be actuated simultaneously together.
For example, the supporting means are movable and/or extendable between a retracted position and a deployed position. For example, they can pivot about a transversal or longitudinal axis, and the angular position can be controlled as a function of the vehicle speed. In another implementation, the supporting means can comprise a hydraulic, pneumatic, electric or mechanical jack whose height can be controlled as a function of the vehicle speed.
According to an embodiment of an aspect of the invention, the cargo body comprises a container having a top wall forming the support suffice, and as flexible cover which is mounted onto the container, on the top wall, and which forms the deformable roof of the cargo body, wherein said flexible cover can be raised above the container top wall when the supporting means are in an aerodynamic position, and wherein said flexible cover can collapse to lie on the container top wall when the supporting means are in a neutral position. By providing a height adjustable additional upper wall, an aspect of the invention makes it possible to modify the roof shape without changing the cargo volume, to reduce the friction resistance.
The cargo body can comprise a container having a floor forming the support surface, and a top wall forming the deformable roof of the cargo body. For example, said top wall can be made of successive semi-rigid panels.
In this embodiment, the supporting means are capable of placing the container top wall in an aerodynamic position which is:                either lower than the neutral position (preferably at the rear portion of the cargo body). In this case, the cargo volume is adapted to the charge by giving the rear part of the roof a lowered profile which makes it possible to reduce the pressure resistance;        or higher than the neutral position (preferably at the front portion of the cargo body).        
By providing a roof having both a lowered rear portion and a raised front portion, an aspect of the invention provides a vehicle with a cargo body having a roof intended to reduce both pressure and friction resistance.
In a vehicle having a flexible cover, the supporting means can comprise a plurality of substantially parallel members arranged transversally, respectively longitudinally, wherein said members can simultaneously pivot from a retracted position, where said members lie substantially parallel to the container top wall, and a deployed position, where said members stand at an angle with respect to the container top wall, the members having different heights depending on their longitudinal position, respectively having a variable height along their length, so that, when the members are in the deployed position, the flexible cover has an aerodynamic shape.
Said members for example comprise plates and/or bended tubes linked together by at least one pulling means such as a cable.
When the cargo body includes a container whose top wall forms said deformable roof, the supporting means can comprise a plurality of substantially vertical jacks which can be retracted or deployed in order to pull downwards or push upwards the deformable roof.
Besides, the cargo body preferably comprises a rear door and means for varying the rear door height to accommodate the variation in position of the deformable roof in the rear portion of the cargo body.
For example, the rear door comprises a flexible panel which can be wound as a roller. Alternatively, the rear door comprises a main panel and an additional panel which is slidably mounted on the main panel in the vertical direction.
These and other features and advantages will become apparent upon reading the following description in view of the drawing attached hereto representing, as non-limiting examples, embodiments of a vehicle according to an aspect of the invention.